Being the 'king of the jungle' is not as fun as it sounds. An international research team has just published a paper in Science showing that most of the 31 largest mammal predators on Earth are in dire straits.

Tigers in trouble (photo by Priya Davidar).

These mega-predators, which include tigers, polar bears, wolves and sea otters, among others, are being decimated by habitat loss and human persecution. Only a quarter of the species, such as the American black bear and puma (mountain lion), are showing some signs of population stability.

Most predators are in precarious shape. The tiger, for instance, is clinging to survival in just 7% of its original geographic range and just 5% of its original numbers.

The authors go beyond describing the ongoing decline of big predators; they also highlight the varied ecological consequences. Large predators can play a dominating role in ecosystems, having profound impacts on many other species and ecosystem processes.

One of the coauthors of the study, Euan Richie of Deakin University in Australia, has written a lively summary of its key conclusions and implications.

Clearly, one of the greatest challenges humankind faces is maintaining living space for species that need large expanses of habitat to survive.